1. Field of the Invention
This invention relates generally to an improvement in a loom equipped with a weft picking control system, and more particularly to the weft picking control system arranged to control the operation of the loom in accordance with the discrepancy between actual force of a picked weft yarn and a standard force thereby to maintain weft picking in a suitable condition.
2. Description of the Prior Art
A variety of weft picking control systems of looms have been proposed to attain good weft picking. One of these is disclosed, for example, in U.S. Pat. No. 4,446,893 entitled "Method for Transporting a Weft Thread through the Weaving Shed of a Weaving Machine through the Intermediary of a Flowing Fluid, and Weaving Machine adapted for the Application of this Method". The weft picking control system in this U.S. patent is arranged as follows: A weft yarn is picked into the shed of warp yarns under the influence of transporting fluid ejected from a plurality of nozzles, in which the transporting speed or time of the picked weft yarn is measured by detecting a timing at which the tip end of the weft yarn reaches an anti-weft picking side from a timing of starting of weft picking. The revolution speed of a main shaft of the loom or the transporting speed of the weft yarn is controlled in such a manner that the measured time occupies a predetermined fraction of time in a weaving cycle. This is effective for reducing mispick.
Here, it is to be noted that, in order to improve the quality of woven cloths, it is required to uniformalize the tension of weft yarns and the tension of warp yarns. This for the warp yarn can be met mainly by high performance control of feeding the warp yarns while this for the weft yarns can be met mainly by high performance control of weft picking.
In this regard, the above-mentioned conventional weft picking control system disclosed in the United States Patent is so configurated as to make constant the timing at which the picked weft yarn reaches the anti-weft picking side, so that the tension of the picked weft yarn is not directly detected. Accordingly, if the reaching timing is controlled to be constant, the tension of the picked weft yarn unavoidably varies in case where a weft package is substitued by a new one in which the tension of the weft yarn wound in the weft package varies depending upon different weft packages Thus, it will be difficult to obtain high quality woven clothes by using such a conventional weft picking control system.